When we used J2205 machine-printed whiteboard paper, serious overprinting inaccuracies occurred. Take a stack of paper, align the sides of the mouth, and follow the stairs. After that, the crosshairs in the middle of each piece of paper are not on a straight line, both sides are.
Checking the components of the transfer station, no abnormalities were found, and the timing of the arrival of the paper was also accurate. It is likely that there was a problem with the delivery time. Then check the hand-over situation, but found that the transfer paper tooth and the imprinting roller edge collision phenomenon, delivery paper touch roller edge is certainly not set. Previously printed 80g/m2 offset paper had a slight overprinting inaccuracy phenomenon, due to the use of whiteboard printing, so the performance is more obvious.
According to the machine factory requirements, at the time of handover, the tip of the transfer paper should be at a distance of 1 to 1.5 mm from the front edge of the impression cylinder. The occurrence of this phenomenon should be caused by the wear or damage of the relevant parts. We have inspected the swing teeth of the paper-transmitting teeth, the rollers of the paper-transmitting swing arms, the pins, the shafts, and the eccentric sleeves on the swing shaft. All of them have different degrees of wear, and the swing arms are rolling. The child has a large gap at the lowest point of the delivery swing cam. According to the requirements of machine design and manufacturing, if the manufacturing precision of the over-cam is high, there is no radial runout of the swing arm roller, and there should be no gap at the lowest point of the cam. Replacing related parts is not only time-consuming and costly, it is not economical. It has been proposed to move the transfer piece backward, but this will reduce the contact area between the pad and the chip, reducing the amount of pick-up, and may cause other problems. According to the analysis of the mechanical principles of printing, the occurrence of such a collision problem is obviously caused by the shortening of the arc travel of the paper-feeding tooth movement, the insufficiency of the pendulum, and the occurrence of hysteresis. Rotate the paper-handling tooth to swing the cam to make it turn clockwise a little and re-drill the hole so that the paper-feeding tooth is 1~1.5 from the front of the impression cylinder.